Drug delivery device and loading cassette management method

Even in the case of a cassette loading section into/from which an established drug cassette is loaded/unloaded, the loading of an optional drug cassette is made possible. If a control means (7) determines that an established drug cassette (16A) has been loaded into a cassette loading section (15) at the established position of a device body (2), the control means (7) determines whether or not the established drug cassette (16A) is loaded into a proper position on the basis of loading destination information stored in a first storage means (18), and the positional information of the cassette loading section (15) into which the established drug cassette (16A) is loaded. Meanwhile, the control means (7) determines that the optional drug cassette has been loaded into any one of the cassette loading sections (15), the control means (7) associates drug related information stored in the first storage means (18) of the loaded established drug cassette with the loading destination information, or the positional information of the cassette loading section, and stores the associated information in a second storage means (32).